Thapsigargin enhanced chemotherapeutic sensitivity of irinotecan in the inflammation-induced colorectal cancer model in mice

The present study used an in-vivo inflammation-induced colorectal cancer (CRC) model to evaluate the additive effect of thapsigargin (TG) with the standard chemotherapy drug irinotecan (IRN). CRC was induced by AOM/DSS, and after 10th weeks, animals were treated with five weekly cycles of either IRN or TG or a combination of both drugs. All the animals were sacrificed after the 16th week, and the data were analysed. Coadministration of both IRN and TG substantially reduced both tumor numbers and occurrence of aberrant crypt foci (ACF) in the colon tissues as compared to only IRN/TG-treated animal groups. Further analyses revealed that IRN and TG together alleviated ultrastructural abnormalities of the colon with a recovered overall histoarchitecture, enhanced ER stress and mitochondrial dysfunction, reduction of PCNA positive cells indicating low rate of cellular proliferation, increased DNA fragmentation and apoptosis supported by higher intensity of γH2AX and cleaved caspase-3 immunohistochemistry. Gene expression analyses of key oncogenic biomarkers also suggest that the addition of TG with IRN is more effective in inhibiting carcinogenic transformation in the colon of AOM/DSS-treated mice. This study provides direct evidence of the superior therapeutic potential of a combination of both drugs compared to conventional monotherapy in the management of CRC.